Powers:Greystone can increase his body mass, density, durability, stamina and strength exponentially but at a price: the bigger he gets, the more deformed and horrific-looking he becomes. Greystone can appear as his host body or in his original body—humorously a small, white child—also carrying the memories from both bodies.

Bio:Greystone is from the same alternate future as Bishop, Archer, Fixx, and Shard. He is a member of the Xavier Underground Enforcers (XUE), a rogue branch of the Xavier's Security Enforcers (XSE) who wanted to travel back in time and change their future.

When he was a child, Greystone lived with his mother in a type of mutant concentration camp. As part of their punishment, each prisoner was required to have an "M" branded over their right eye to outwardly signify their status as a mutant. During his branding process by an evil man named Micah, Greystone panicked and—due to the large amount of stress—manifested his mutant power years before the traditional onset at puberty. This resulted in him breaking the machine (leaving him with only a partial brand), and trying to break out with his mother. Micah shot and killed her and was about to kill Greystone too if not for the incitement of the Summers Rebellion which ultimately led to mutant freedom. However, this was not as grand as it seemed, for Greystone became an orphan and a street urchin outside of the confines of the camp.

Upon discovering that Shard was in the present, the X.U.E. managed to travel back in time due to the psionic link Fixx created between the members of the X.U.E. which Shard was also a member of, and inhabited the bodies of three recently deceased people. Greystone inhabited the body of the adolescent teen Brian Young.

While looking in the newspaper one day, Greystone happens to see the picture of a young boy named Micah. He immediately recognizes him as the same Micah who murdered his mother and concocts a plan to murder the child, thus averting his future and his mother's death. He, along with Fixx and Archer, track down the boy and Greystone tries to kill him. Archer and Fixx convince him that it is unethical to condemn the child for crimes he has not yet committed and the trio leaves. They had tried to change the future but instead ended up joining X-Factor.

Greystone slowly developed temporal insanity, believing that his mission was accomplished, and he could go home to a better world and be reunited with his mother, who might theoretically be alive. In an attempt to return to his own time, Greystone built a flying time machine, but due to shoddy craftmanship and unsound theories, the craft exploded, seemingly killing Greystone and Havok, who was attempting to stop him.